feat: consolidate page-cro and form-cro into unified cro skill

- Create skills/cro/ with shared CRO analysis framework
- Move page-specific content to references/page.md
- Move form-specific content to references/form.md
- Copy experiments reference from page-cro
- Remove skills/page-cro/ and skills/form-cro/
- Update all cross-references across skills, tools, README, AGENTS.md

BREAKING: page-cro and form-cro are replaced by cro.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tools/integrations/ga4.md

@@ -123,4 +123,4 @@ POST https://www.google-analytics.com/mp/collect?measurement_id={measurement_id}
 - analytics
 - ab-testing
 - seo-audit
-- page-cro
+- cro

tools/integrations/google-ads.md

@@ -156,4 +156,4 @@ LIMIT 10
 
 - paid-ads
 - analytics
-- page-cro
+- cro

tools/integrations/hotjar.md

@@ -140,7 +140,7 @@ Authorization: Bearer {access_token}
 
 ## Relevant Skills
 
-- page-cro
+- cro
 - ab-testing
 - analytics
 - ux-audit

tools/integrations/meta-ads.md

@@ -144,4 +144,4 @@ access_token={access_token}
 
 - paid-ads
 - analytics
-- page-cro
+- cro

tools/integrations/optimizely.md

@@ -165,7 +165,7 @@ GET https://api.optimizely.com/v2/pages?project_id={project_id}
 ## Relevant Skills
 
 - ab-testing
-- page-cro
+- cro
 - landing-page
 - personalization
 - analytics

tools/integrations/plausible.md

@@ -173,5 +173,5 @@ GET https://plausible.io/api/v1/sites
 - analytics
 - content-strategy
 - programmatic-seo
-- page-cro
+- cro
 - utm-tracking

tools/integrations/typeform.md

@@ -185,6 +185,6 @@ GET https://api.typeform.com/workspaces/{workspace_id}
 
 - lead-generation
 - customer-research
-- page-cro
+- cro
 - signup
 - customer-feedback

tools/integrations/webflow.md

@@ -195,4 +195,4 @@ webflow devlink sync
 
 - programmatic-seo
 - content-strategy
-- page-cro
+- cro